1. Field of the Invention
This invention relates generally to automatic door actuator systems for swinging doors and more specifically to a retroflective presence sensing apparatus for such systems wherein the presence sensing apparatus is recessed within the muntin of a swinging door and is operable to detect the presence of objects in proximity to the door and generate signals to an automatic door operator to control the opening and closing of the door accordingly.
2. Description of the Related Art
Automatic door actuator systems are advantageously utilized in entry and exit ways having pedestrian traffic. Such systems are also often used to advantage where pedestrians entering or exiting a building or facility may be expected to be carrying or otherwise transporting a load which would prevent them from conveniently operating a manual door. Such situations are commonly found at shopping centers, supermarkets, and the like. Such systems are also advantageously used where it is simply desired to provide added convenience to a pedestrian entering or exiting a building, or where it may be expected that the pedestrian may, for some reason, be physically unable to manually open or close a door.
Typically, an automatic door actuator system includes sensors for detecting the presence of persons or objects within selected areas on both sides of the door, and a mechanical operator which is responsive to signals from the sensors to open and close the door. The door itself is typically of the swinging variety. Schroeder U.S. Pat. No. 3,003,317 discloses a wellknown type of swinging door actuator system that utilizes pressure-sensitive mat switches located under mats on the entrance (or approach) and exit (or safety) sides of the door, and a motor driven hydraulic door operator which is responsive to signals from the mat switches. In this system, the mat switches generate control signals in response to pressure from persons or objects to cause the operator to automatically open and close the door.
Despite the basic functionality of this system, it is subject to certain drawbacks. For example, the mats used in such systems can become worn or inoperative with use, thereby necessitating periodic repair or replacement. Moreover, worn mats may prevent the accurate generation of appropriate control signals. The mats of such systems also have a certain elevation with respect to ground level which may cause pedestrians to trip and which present an undesirable obstacle to wheeled vehicles such as grocery carts and wheel chairs, for example. Additional effort is often required to push such wheeled vehicles over the edges of such mats and there is a possibility that the edges of such mats could cause the upending of such wheeled vehicles.
Another type of known actuator system for a swinging door utilizes microwave motion detectors mounted on the approach and safety sides of the door. The detectors establish detection zones on both sides of the door. When a detector detects motion in its detection zone, it generates control signals that cause an operator to open or close the door.
This type of actuator system is also subject to certain limitations. For instance, the sensors of this system respond only to detected motion. Therefore, a person present but not moving in a detection zone may not be detected.
Another type of known actuator system for a swinging door is described in Kornbrekke U.S. Pat. No. 4,565,029, and Jonsson U.S. Pat. Nos. 4,590,410; 4,560,912; and 4,467,251. This type of system utilizes infrared emitters (LED's) and detectors (photodiodes) as sensors, and motors as operators. An operator control which is responsive to signals from the sensors to control the door operator is also provided.
Kornbrekke discloses a system in which a plurality of emitters and detectors are mounted externally on opposite vertical jambs on both sides of the door. The emitters establish detection zones on both sides of the door. A person or object in a detection zone reflects infrared radiation from an emitter and the reflected radiation is detected by the corresponding detector. The detectors generate signals which cause the operator to open and close the door. The Kornbrekke operator includes an optical encoder mounted on the armature of the motor which generates pulses indicative of discrete positions of the door. The door position signals are used to enable and disable selected emitters as the door opens and closes to prevent improper detection of the door itself.
The Jonsson patents disclose a system in which a plurality of emitters and detectors are externally mounted linearly in a horizontal plane on both sides of a swinging door. The emitters generate diverging beams of diffuse (rather than focused) radiation and the detectors detect the presence of persons and objects and generate door control signals to which a door operator control is responsive to cause a door operator to open or close the door. In the Jonsson actuator system, a door position switch is provided that is actuated by the door operator or the door itself when the door has opened to a selected angle. After the position switch is actuated, the sensitivity of the detectors are reduced to prevent improper detection of the door itself.
Both the Kornbrekke and Jonsson systems have certain limitations and drawbacks which restrict their usefulness and effectiveness. For instance, in order to provide adequate detection zone coverage both systems require placement of the sensors on external areas of the door or jambs in locations where they are exposed to contact with pedestrians as well as wheeled vehicles such as shopping carts and wheel chairs. Thus, the sensors of these systems are constantly exposed to damage during operation. Also, both systems are too rigid in the approach taken for preventing detection of the door itself or other surroundings. In the Kornbrekke system, only emitters are selectively enabled and disabled. In the Jonsson system, the sensitivity level of all detectors is reduced when the door exceeds a selected open position. In addition, the infrared sensors of such systems may have difficulty detecting some objects such as shopping carts approaching or near the door.